I am running my HD6870s in crossfire on a Corsair TX650 and it is a bit warm and consequently a little noisy but is stable. It is probably getting close to (or at) the maximum capacity of the unit, so for overclocking my GPUs I intend on replacing it with a Silverstone Strider Plus 850w.
Wattage is not as important as amps, but any top brand PSU at 750w or 850w is going to have plenty. I don't really understand why people with less components than myself are buying 1000 or even 1200 watt power supplies, seems like money better spent elsewhere. Besides, if you buy a 1000w Gold rated PSU and its only running at say 50% capacity because you don't have enough equipment, it won't run at the rated efficiency of Gold, which kind of defeats the purpose. I would suggest the 850w Strider Gold or Plus you have linked to above, you can't really get a better power supply for the money and it is as good as more expensive units from Corsair and Enermax (based on AU pricing).